You've heard of the gryphon, the dragon, and the basilisk, but they're nothing compared to the bonnacon:

The bonnacon is a beast with a head like a bull, but with horns thatcurl in towards each other. Because these horns are useless fordefense, the bonnacon has another weapon. When pursued, the beastexpels its dung which travels a great distance (as much as two acres),and burns anything it touches. -- The Medieval Bestiary